16th IFOAM Organic World Congress, Modena, Italy, June 16-20, 2008
Archived at http://orgprints.org/12304
Nitrogen Utilization in Integrated Crop and Animal Production
Seuri, P.
Key words: nitrogen utilization, nutrient circulation, integrated production
Abstract
The principles of organic production are based on integration between crop and
animal production and self-regulated nutrient intensity. A comparison between
specialized dairy and crop farm models and an integrated dairy and crop farm model
showed 24 % higher total production per area and higher nitrogen utilization in the
integrated system. The main factors were more efficient nutrient circulation, better
utilization of legume crops and low intensity of nitrogen on non-legume crops.
Introduction
The main factors influencing nutrient utilization in agriculture are the production line
(crop vs. animal production) and the degree of intensity and specialization of
production. Organic production is based on integration between crop and animal
production and self-regulated nutrient intensity. However, many organic farms are
specialized in crop production based only on green manure and farm yard manure
(FYM) from neighbouring farms. On the other hand, animal farms widely use
purchased fodder. All of this may effect the utilization of nutrients, yet hardly any
comparisons or analytical surveys between specialized and integrated (organic) farms
can be found in literature.
The aims of this study were:
a) To model specialized organic crop and animal farms and an integrated farm
b) To identify the differences in nutrient balances and utilization between the models
c) To optimize nutrient utilization by means of integrating crop and animal production
Material and methods
A more detailed analysis was made of nitrogen (N) utilization on 9 organic farms in
eastern Finland. The farmers were personally interviewed in 2004 and all the main
nutrient flows were identified for the years 2002-2004. The assumption of a steadystate with balanced systems and reserve nutrients in the soil was applied. Biological N
fixation (BNF) was assumed to account for 70 – 90 % of the total nitrogen content in
the legume biomass (Kristensen et al. 1995, STANK 1998, Väisänen 2000). Red
clover, white clover and alsike clover were grown in perennial mixture leys. Pea and
annual vetch were annual legumes. (Seuri 2005).
Equal amounts of milk, beef and bread cereal were produced either on a specialized
dairy farm (D) model and a specialized crop farm (C) model jointly or on an integrated
dairy and crop farm (I) model. The share of fodder production was 80 % and bread
cereal 20 % of the total yield, based on the average Finnish diet and use of arable
land. BNF and atmospheric deposition (5 kg/ha annually) were the only external inputs
of nitrogen (=primary nitrogen) in both systems. On farm C, all the harvested yield was
MTT Agrifood Research Finland,
pentti.seuri@mtt.fi, Internet www.mtt.fi
Karilantie
2A,
FI-50600
Mikkeli,
Finland,
E-Mail
16th IFOAM Organic World Congress, Modena, Italy, June 16-20, 2008
Archived at http://orgprints.org/12304
sold (either to farm D as fodder or outside the system as bread cereal) and no FYM
was used. On farm D, all the harvested yield was used as fodder. In addition, about 20
% of the fodder was purchased from farm C. All of the FYM was used only on farm D.
On farm I, no fodder was purchased, but 20 % of total yield was sold as bread cereal.
Results
The major characteristics of the farm models are presented in Tables 1 and 2; more
detailed N utilization is presented in Table 3.
Tab.1: Characteristics of three farm models: Specialized Dairy Farm (D),
Specialized Crop Farm (C) and Integrated Dairy and Crop Farm (I). Both of the
dairy farms (D & I) keep equal numbers of calves for replacement, all others are
sold immediately after the suckling period. Replacement of the cows takes place
after three milking periods.
D
Crop rotation / (crops %)
ley / green fallow
cereals
rape seed
cereal+peas
Legumes % / non-legumes %
Yield level (FU/ha & N kg/ha)
ley /(green fallow)
cereals
rape seed
cereal+peas
Harvested N yield (kg/ha)
Animal density (AU/ha
Milk yield (kg/cow)
C
I
3 yrs. (60%)
2 yrs. (40%)
60 / 40
2 yrs. (40%)
2 yrs. (40%)
1 yr. (20%)
40 / 60
2 yrs. (40%)
2 yrs. (40%)
1 yr. (20%)
60 / 40
3200 & 85
2200 & 42
68
0.71
7350
(green fallow)
2200 & 42
1800 & 42
25
-
3200 & 85
2000 & 38
2000 & 52
60
0.43
7000
Tab. 2: Legume yields and BNF on farm models.
C*, no legume yield is harvested, but ploughed in as green manure; only the
first year ley exists (twice in 5-year-rotation) on farm C.
Crop
First-year ley
Second-year ley
Third-year ley
Cereal + peas
Farms D & C*
Yield (FU/ha)
3600
3200
2800
-
Farm I
Yield (FU/ha)
3400
3000
2000
Farms D, C & I
BNF (N kg/ha)
120
80
40
40
The total average BNF is equal (48 kg/ha) in all the farm models. However, there is
quite great variation between N intensity on non-legumes (=manure or green manure
for non-legumes). The N intensity on non-legumes is highest on farm D (100 kg/ha),
due to high amount of manure on a limited non-legume area (40%). Also on farm C
the N intensity is higher (80 kg/ha) on non-legumes than on farm I (65 kg/ha). (Tab. 3).
Due to the lower N intensity on non-legumes, 10 % lower crop yield is assumed on
farm I than on D and C (Tab. 1.).
16th IFOAM Organic World Congress, Modena, Italy, June 16-20, 2008
Archived at http://orgprints.org/12304
Despite the lower yield level because of lower N intensity on non-legumes, the
average total production is higher in integrated production (I) than in specialized
production (D+C). More arable land, 24 %, is needed on the specialized farms than on
the integrated farm to produce an equal “food basket” (milk, beef and (bread)cereal)
(Tab. 3.). This is due to the green fallow on the specialized crop farm.
Tab. 3: N flows and balances in three model systems. Comparison by equal total
production, I vs. D+C (sum of 0.57 ha D and 0.67 ha C equals 1 ha I); and by
equal area (1 ha).
Note: System boundaries are slightly different between EP and EA (bolded figures);
e.g. purchased fodder in EP is not an input or output, but within system boundaries as
it is purchased from farm C; in EA it is external input (farm D) and output (farm C).
Equal production (EP)
symbol
Harvested N yield
1
Y
N intensity on non-legumes 2
Equal area (EA)
I
D+C
D
C
D
C
unit
(1 ha)
(1.24 ha)
(0.57 ha)
(0.67 ha)
(1 ha)
(1 ha)
(kg N)
60
56
39
17
68
25
(kg N/ha)
65
89
100
80
100
80
Deposition
p1
(kg N)
5
6
3
3
5
5
BNF
p2
(kg N)
48
60
28
32
48
48
51
47
47
F
(kg N)
Fodder harvested
Fh
(kg N)
51
-
39
Fodder purchased
Fp
(kg N)
-
-
8
M
(kg N)
FYM (fodder harvested)
m
(kg N)
26
-
19
FYM (fodder purchased)
p3
(kg N)
-
-
4
Losses outside field 3
L
(kg N)
13
12
12
Animal products sold
A
(kg N)
12
12
12
Crop products sold
C
(kg N)
9
9
Primary N ( = p1+p2+p3)
P
(kg N)
53
66
31
Secondary N (=M-p3)
S
(kg N)
26
23
23
1.75
Total fodder
FYM ( = F-A-L)
Circulation factor (P+S)/P
Farm gate balance p1+p2+Fp-C-A
26
23
82
68
14
23
40
33
7
21
21
9 (+8)
35
25
60
53
33
(-)
1.49
1.35
1.55
1
(kg N)
32
45
46
28
0.47
output/input (C+A)/(p1+p2+Fp)
1
(-)
0.39
0.32
0.32
Field balance p1+p2+M-Y
(kg N)
19
33
25
28
output/input Y/(p1+p2+M)
(-)
0.76
0.63
0.73
0.47
1.13
0.85
1.14
0.47
4
PPB = Y/P
(-)
1.25
0.47
1 See table 1.
3 40 kg N/cow (incl. young cattle for replacement) (Grönroos et.al. 1998)
2 FYM or green manure N for non-legumes
4 Primary production balance (Seuri 2005)
The nutrient balances describe the nutrient utilization, whereas comparison by area
does not show any clear difference between the models. Comparison by equal total
production indicates better utilization on the integrated farm than on the specialized
farms jointly by all the indicator balances used (farm gate balance, field balance,
PPB). The difference between primary N is 24 % (53 kg vs. 66 kg) for equal total
production.
The major difference between these two production strategies is nutrient circulation. In
the integrated system (I) the circulation factor of N is as high as 1.49. In the
specialized system (D+C) it is clearly lower, 1.35. Another major difference is the poor
field balance (0.47) in the specialized crop production compared to the field balance in
the integrated system (0.76). This indicates the importance of utilization of legume
16th IFOAM Organic World Congress, Modena, Italy, June 16-20, 2008
Archived at http://orgprints.org/12304
yield. On farm C, no legume yield is utilized as a final output of the system, but only as
a source of N for a non-legume cash crop.
Conclusions
N intensity is highly dependent on the proportion of legume crops in the crop rotation.
However, with increasing proportion of legumes in the crop rotation, the risk of serious
pathogen problems increases. Generally, the maximum proportion of legumes in crop
rotation is around 60 %. Model D is based on this hypothetical maximum legume area.
In addition, the amount of FYM is increased by 20 % using purchased fodder. Farm D
has a slightly higher circulation factor and PPB than farm I, and the total yield is also
slightly higher. Since the final products of these two farms are not equal, the
comparison is misleading.
Model C is based on a minimum legume area, since legume crops are not cash crops
at all. Hypothetically, a slightly lower N intensity on non-legumes could be possible.
However, the risk of total crop failure and poor quality of yield in unfavourable weather
conditions increases drastically. The poor PPB (0.47) reflects the weakness of the
system: no nutrient circulation at all and no direct utilization of legume crops.
Model I is run with the lowest possible N intensity on non-legumes. However, the risk
of total crop failure and poor yield quality can be controlled with help of
(ruminant)cattle. The circulation factor is lower than in model D because of the 20 %
cash crop area. However, legume crops are managed more efficiently resulting in the
highest field balance (0.76). In order to produce the given “food basket”, this model is
superior to the specialized alternative (D+C). According to the present data, this model
has close to optimum N utilization. However, other nutrients must be replaced by
completing nutrient recycling or from external sources.
References
Grönroos, J., Nikander, A., Syri, S., Rekolainen, S. & Ekqvist, M. 1998. Maatalouden
ammoniakkipäästöt. Suomen ympäristö 206. (English abstract: Agricultural ammonia
emissions in Finland.)
Kristensen, ES., Högh-Jensen, H. & Halberg, N. (1995) A simple model for estimation of
atmospherically-derived nitrogen in grass/clover systems. Biol Agric Hortic 12: 263-276.
Seuri, P. (2005) Evaluation of nitrogen utilization by means of the concept of primary nutrient
efficiency. In Granstedt, A., Thomsson, O. and Schneider, T. (eds.) . Environmental impacts
of eco-local food systems – final report from BERAS Work Package 2. Baltic Ecological
Recycling Agriculture and Society (BERAS) Nr. 5. Ecological Agriculture nr 46. Centre for
Sustainable Agriculture. Swedish University of Agricultural Sciences. P. 36 – 42.
STANK. 1998. Statens Jordbruksverks dataprogram för växtnäringsbalansberäkning. Stallgödsel
och växtnäring i krettslopp (STANK) Jordbruksverket, Jönköping. (Plant nutrient balance
calculation program)
Väisänen, J. (2000) Biological nitrogen fixation in organic and conventional grass-clover swards
and a model for its estimation. Licentiate’s thesis. University of Helsinki Department of Plant
Production Section of Crop Husbandry. 42 p. + 2 app.